His portrait gazes down on Tiananmen Square in the heart of the capital. His picture is emblazoned on every banknote. But to one military man, Mao Zedong has a special place: not just as the founder of China but as his grandfather.

Now Mao Xinyu, the Great Helmsman's only grandson, is making waves himself following an apparent promotion to major-general, at 39, the youngest in the People's Liberation Army.

His elevation has not been announced formally, but state media said he was recently introduced by the new title while making a speech as a researcher for the Academy of Military Sciences.

The news comes ahead of 1 October celebrations marking 60 years since his grandfather proclaimed the founding of the People's Republic.

Mao Xinyu appears to be the very model of a modern major-general, with his own blog. In addition to his official duties he works to uphold the family name, having written a biography, Grandfather Mao Zedong, and sung songs in his honour.

In an interview with Southern People Weekly last week, Mao said he had hoped to continue researching classical literature: "But my mother firmly required me to study Mao Zedong thought. Now I see this was a completely correct decision."

He added: "It was after joining the army that I began to really understand grandpa. If I hadn't joined the army and the party, I would feel more relaxed when facing grandpa, just like a grandson in an ordinary family.

"However, I couldn't. As a soldier, I regard him as our leader and commander-in-chief."

Mao Xinyu is the child of Mao's son Anqing, borne by his second wife Yang Kaihui, who was killed by a warlord in 1930, aged 29. Mao Anqing died two years ago, aged 84. Mao Xinyu's mother Shao Hua became a major-general in the PLA in 1995.

Mao's granddaughter, Kong Dongmei, has also written about her forebear in books including Open My Family's Old Photo Album: Grandfather Mao Zedong in My Heart, although she never met him.

In an interview with a Chinese paper three years ago she described him as "a son, a husband and a father first, a statesman second".

Her mother, Li Min, and aunt, Li Na, are members of the Chinese People's Political Consultative Conference, an advisory body to the country's largely rubber-stamp parliament. Li Na has said that Mao was very strict with his children, telling a Chinese newspaper: "He didn't wish for us to become famous. He only wanted us to work with our own hands. He said he would be satisfied if we could become common labourers."

None of them followed quite that path, but unlike the offspring of other top party leaders, they did not end up as business tycoons.

The family's political commitment is likely to continue: Mao Xinyu said he would like to take his six-year-old son to revolutionary sites once he grew a bit older, and allow him to study Maoist thought once he turned 15.

"I will let Dongdong become both an outstanding successor of a great leader and an ordinary member of the public," Mao Xinyu said. "I don't want to restrict him too much. But frankly speaking, I hope he joins the army."